Dynamic modelling and thermoeconomic analysis of micro wind turbines and building integrated photovoltaic panels

During the past few years a significant effort has been performed in order to promote the use of renewable energy sources. However, one of the main barriers for a mature commercialization is due to the unpredictability of the renewable power production, mainly in case of wind and solar energy. Unfortunately, electric storage devices are often poorly profitable. Therefore, some more stable renewable energy systems must be designed. In this framework, this paper presents a novel hybrid renewable system consisting of Building Integrated PhotoVoltaic panels and small-scale Wind Turbines and double-stage heat pumps. This combination is very promising since it reduces the typical fluctuations of solar or wind systems, achieving a more stable profile of the overall power production. A detailed dynamic simulation model is developed in TRNSYS environment, including validated models for all the components and a suitable thermoeconomic analysis. A case study is implemented for a hotel building, where the space heating and cooling energy is supplied by an electrically driven reversible air-to-water Heat Pump, supplied by the electricity produced by Building Integrated PhotoVoltaic panels and Wind Turbines. the thermal energy recovered from the HP desuperheater is coupled with the thermal energy produced by a two-stage cascade cycle Heat Pump to produce domestic hot water. Results are presented in terms of hourly, monthly and yearly system performance data as well as by discussing the results of a detailed sensitivity analysis performed to detect the optimum configuration and weather zone of this hybrid renewable system. An analysis of the building envelope features is also performed, according to the nearly zero energy buildings target. Results showed that the combination of photovoltaic and wind technologies allows one to significantly enhance the stability of the renewable power production. Results also show that the use of heat pumps leads to a reduction of the primary energy demand for building space heating/cooling and domestic hot water by 30%. A payback period of about 5.2 years is obtained and the optimum configuration suggests adopting one 20 kW Wind Turbine for the selected case study.